


Baby Fever

by memoriesofrain



Category: Shadowhunters (TV), The Shadowhunter Chronicles - All Media Types
Genre: Alec Lightwood Deserves Nice Things, Alpha Magnus Bane, Alpha/Beta/Omega Dynamics, Alpha/Omega, Bottom Alec Lightwood, Breeding, Communication, Confident Alec Lightwood, Dirty Talk, Domestic Magnus Bane/Alec Lightwood, Happy Magnus Bane/Alec Lightwood, Kink Meme, M/M, Magnus Bane Deserves Nice Things, Male Lactation, Omega Alec Lightwood, Pregnancy Kink, Prompt Fill, Talk of infertility, Top Magnus Bane, at least talk of it, because he's a married man and he and Magnus talk about what they want, because it's sexy, kink meme prompt, shadowhunter kink meme, they both want to start a family
Language: English
Status: Completed
Published: 2020-10-20
Updated: 2020-10-20
Packaged: 2021-03-09 06:54:28
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,309
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27119858
Author URL: https://archiveofourown.org/users/memoriesofrain/pseuds/memoriesofrain
Summary: Alec and Magnus had talked about starting a family before but now that things have settled down in the Shadow World, Alec can't stop thinking about carrying Magnus' child. Lucky for him, his husband is more than okay with trying.
Relationships: Magnus Bane/Alec Lightwood
Comments: 24
Kudos: 293





	Baby Fever

**Author's Note:**

> This is a fill for a prompt I found on the probably abandoned Shadowhunter kink meme:
> 
> [Alec would like nothing more than to be filled up with Magnus's seed and carry his child. Luckily, he's an omega.](https://shadowhunters-kink.dreamwidth.org/715.html?thread=3275#cmt3275)
> 
> I've been working on this off and on, but I figured I should finally just bite the bullet and post this. Before I lost my nerve. I hope you enjoy!

It starts with babysitting.

It wasn’t uncommon for Catrina to drop Madzie off at the loft when she had the graveyard shift or had a convention to attend. And each time Magnus and Alec welcomed her with open arms, thrilled to get to spend time with the little girl.

Alec had even noticed he’d started actively picking up things to have at the loft for when Madzie would come visit. From a new set of colored pencils to a few mermaid dolls that he could play with her with. At first he’d been embarrassed that he’d amassed a small hoard of items for his favorite sorceress, but Magnus had been quick to reassure him that it was a thoughtful gesture.

“You’re just making sure our girl has everything she might want here,” Magnus said, pressing a kiss to his deflect rune before pulling back to rub his nose against Alec’s. “You should never feel embarrassed for being thoughtful, angel.”

Alec didn’t really catch the last part of the conversation, his mind hyper-focusing on Magnus’ claim to Madzie.

_Our girl._

Suddenly his mind was filled with not only Madzie, but little Shadowhunters and warlocks playing together with Magnus’s eyes. Of sticky hands and toothy grins. Of tucking children into bed and Magnus happily nuzzling his belly with that besotted look in his eyes that Alec knows would be reflected in his.

By the angel does Alec want to have Magnus’s child.

Standing bare in front of the mirror, Alec can’t stop himself from bringing his hand up to his stomach and splaying his hand against the flat surface. His skin is warm and the muscles underneath are taunt as they’ve always been, but he can’t stop thinking about a child growing in his womb. _Magnus’s_ child.

Ever since he had the thought it’s like the need to give Magnus a child simmers in his heart. Even the thought of Magnus putting that child in him makes slick trickle from his hole.

They’ve talked about children before, but it was always along the lines of “eventually.” They would _someday_ have children together, start a family. That now that things had settled down they could finally start really talking about expanding their family. But then Magnus would tease that they already had so many children to look after in their line of work that it was like they were already parents.

They’ve also talked about the very real possibility that they may _never_ be able to have a child naturally. Warlocks had a very low fertility rate; that was something that Magnus had told him when they’d first talked about children. Even with Alec’s own high fertility from his Nephilim heritage, it was likely that getting pregnant wouldn’t be easy if possible at all.

But that knowledge did nothing to stop Alec from imagining the possibility of getting pregnant.

He turns to the side and pushes his stomach out as much as he can. The swell of his belly pushes against his hand and he has to bite down on his lip to quiet the whimper that attempts to slip out. He knows that he probably looks at least a little silly, but now he’s imagining its Magnus’s hand on his belly. Those beautiful, strong hands reverently caressing the home of his child. _Their child._

Slick starts down his thigh and Alec is quick to pull his hand away from his stomach and turn the water on. He can feel the heat of his blush in his cheeks but he isn’t sure if it’s because of his fantasizing about carrying Magnus’s child or his reaction to Magnus having bred him.

He’s fucked and he knows it. Now it’s just a matter of time before Magnus figures out Alec’s ever growing desire to be bred.

It took Magnus three days to recognize a change in Alec’s behavior. Alec is sure that Magnus had known something was different when Alec first started hyper-fixating on getting pregnant. Not that he was being overly overt about the whole thing, but Magnus knew him well enough to notice a change in his general routine.

He’d been researching all sorts of ways to boost fertility when he had a spare moment. His lunch breaks had become filled with articles on the right foods to eat to prepare his body for the nutrients it would need to provide for the fetus. His shopping trips consisted of comparing vitamins and figuring out what prenatal vitamins he was going to take when he conceived.

Honestly, Alec was almost embarrassed with how excited he was about even the _thought_ of Magnus breeding him. Almost. The other part of him is proud with how confident and comfortable he’s become with his secondary gender. He never thought he’d ever give into his omega, let alone want to embrace his nature and have a baby with his partner.

He’d grown up doing everything he could to push that side of him down, despite Isabelle doing everything to show him that his secondary gender didn’t define who he was. Omegas were strong and fiercely protective, but Shadowhunters still had an outdated view on them, much like their views on Downworlders.

But Magnus was the one who finally drove that home for him: he was so much more than just an omega. He was the Head of the New York Institute, a strong and respected Shadowhunter who strived to protect everyone.

_He was Magnus’s omega_.

He smiled at his wedding ring and decided he needed to make his desire for a child known to Magnus before he continued all this prep-work.

When he opened the door to their apartment he was greeted with the beautiful sight of his husband, not a hair out-of-place as he zipped around the room, gathering notes and books he’d scattered about their coffee table.

“Alexander,” Magnus greeted, a smile and warm eyes ever-inviting, “Welcome home, darling.”

Alec couldn’t help the goofy smile he made at Magnus’s welcome. “I’m home,” Alec said, walking over to Magnus who’d opened his arms to welcome Alec into his arms. He wasted no time in tucking his nose against Magnus’s neck to scent him and wrapping his arms around the warlock. “How was your day?”

Magnus let out an exaggerated sigh. “Oh you know how it is, mostly just simple customers that I’m more than happy to help and then the last one of the day asks for the moon.”

He hums sympathetically, “Didn’t accept his request?”

“Of course I accepted the job, _after_ I renegotiated the cost of my services.”

“You’re too nice, Magnus.”

Magnus snorted. “Hardly, angel.” The noise ruffled Alec’s hair and he felt amusement tickle at his lips. “I couldn’t just let them go without helping in some way, it’s my job.”

He shrugged. “Job or not, you’re still too nice.”

They stay tucked against each other for a few more moments, enjoying the gentle silence that yawns throughout the loft. They only pull away when they hear a soft mewl from Chairman Meow who is obviously done with not being lavished with attention.

Alec laughs, walking over to the back of their couch that Chairman is currently perched on. “I didn’t forget about you, Chairman,” Alec reassures, scooping the cat up into his arms and tucking the ball of fur against his chest. “I hope you had a good day.”

Magnus shakes his head. “Our baby has been just fine, he’s already wrangled three slices of sashimi from me with those big eyes of his.” He clucks his tongue and waggles his finger at Chairman. “You’re so lucky your daddies love you so much.”

He hums in agreement, stroking Chairman’s fur as he tries to ground himself. _Our baby_. The phrase makes a warmth tingle along his spine and a pleasant buzz to fog his mind.

He’s got baby fever _bad_.

Gently placing Chairman back on the couch, he turns back to his husband. He grabs Magnus’ hands in his own and brings them to his lips, peppering kisses across Magnus’ knuckles. The action draws a besotted look from Magnus and Alec is helpless but to smile back.

Unsure how to bring up the topic, he tugs Magnus to the couch and pushes him to sit down before settling himself in Magnus’ lap, his knees on either side of the alpha’s thighs.

His husband grins, a mischievous glint in his eyes as he lets his hands knead at Alec’s sides. “Someone knows what they want,” he says, mouthing at Alec’s jaw. “And I’m ever eager to please.”

As much as he’d love to let Magnus ravish him, he knows he needs to talk to Magnus about how he’s been feeling, lest he get caught up in the moment and put off talking to Magnus about an addition to the family. He pushes at Magnus’ shoulders until his husband lets up his ministrations.

Magnus is staring at him now, his thumbs stroking his hip bones – to soothe Alec in case he’s upset him. “Everything okay?”

Alec nods his head. “I um- I wanted to talk to you about something,” Alec starts.

“You can always talk to me about anything.”

Moment of truth; Alec takes a steadying breath and grabs one of Magnus’s hands in his own, twining their fingers together. “Have you…” It shouldn’t be this hard, but it’s Alec and he’s always had trouble coming out with what he wants. That hasn’t gotten much better even after being with Magnus for so long.

Luckily, Magnus has endless patience when it comes to Alec’s struggle.

He clears his throat and steals himself. “Magnus, I want a baby.” Magnus’s ministrations come to a halt as he blinks owlishly at him. Alec blushes under the look, but plows on. “I- We’ve talked about it before and I know we haven’t really brought it up since then but I’ve been doing a lot of research about ways to boost fertility and what prenatal vitamins I’ll need to take once I’m pregnant and-“

Magnus stops the beginning of his ramble with his lips and Alec melts into the kiss. His alpha continues the languid glide of their lips and pulls Alec closer to his chest. When they pull apart, its beautiful, golden cat eyes that stare into Alec’s own. “You want a baby?” Magnus asks, a smile pulling at his lips.

Alec laughs and nods his head, biting lightly at his lip as he fights a grin. “I _really_ want a baby.” He lets his arms circle Magnus’s neck and rolls his hips experimentally, sighing as the action is met with a small thrust from the man under him. “Ever since the last time we babysat Madzie, all I’ve been able to think about is how much I want to have a baby with you.”

His declaration earns him a soft groan from his husband and a nip at the place right underneath his ear. “All you’ve been thinking about, huh?”

He nods, tilting his head to the side to allow Magnus to continue his ministrations along his neck. “Keep thinking about you breeding me, filling me up with your seed,” Alec says, feeling his slick begin to trickle out of him and for a moment he wonders if his heat is coming early with how fast his body is responding. “Keep thinking about how I’ll look when I’m carrying our child. How everyone will see my belly and know how well my alpha has bred me.”

Magnus runs his hands down Alec’s back, his nails creating a pleasant tingle down his spine. “You’d look stunning, angel.” He says it with such reverence, as if the very thought of Alec carrying his child is enough to do him in.

Maybe Alec hasn’t been the only one suffering from baby fever. “Would bask in the feeling of our child getting bigger every day, knowing that we’ve made them together,” Alec says, pressing a kiss to Magnus’s temple as the alpha starts to mouth at the junction between his neck and shoulder.

His husband circles his nipple though his shirt with a ringed finger, every few circles running a nail over the hardened peak. “These would change too,” Magnus says, pinching the neglected nipple.

Alec shudders at the pleasure-pain that the action causes. “To provide for our baby.”

Magnus bumps their noses together, his eyes sparkling. “I would of course, have to do a quality test every once in a while, to make sure our baby was getting the best milk.”

He guffaws, slapping Magnus’s shoulder. “Oh would you now?” Magnus hums with a grin. “Don’t think I’ll be making exactly what our baby needs?”

“Oh I’ve no doubt these will fill up with only the best.” His alpha cups Alec’s pecs, “I just want an excuse to enjoy my beautiful, bred omega to the fullest; and that, of course, involves tasting your milk.”

“Of course,” Alec says sagely, his cheeks hot. A few years ago and that would’ve left him a flustered mess and uncomfortable. “Will you still want to fuck me when I’m pregnant?”

Magnus knows he’s joking but the little growl that his alpha lets out makes him smile. “Alexander, there is no world in which I will _not_ want you. And when your belly is heavy with our child and your breasts are full of milk? Angel, I’ll be _insatiable_.”

Alec practically purrs at the declaration and by now he can blatantly tell that he’s soaked through his underwear as slick continues to trickle out of him. “Why don’t we start now?” Alec suggests grinding down against Magnus. “Fill me up with your seed, alpha.” He looks directly into Magnus’s heated gaze as he tips his head to the side. “Breed me.”

Magnus is hefting him up before he can say anything else, his hands cupping Alec’s ass as he carries him to their bedroom. Every time the warlock lifts him up like he weighs nothing, Alec’s pulse races.

His alpha doesn’t even pause as he lays him down on the bed before crawling on top of him. Wet kisses are given generously down his neck and Alec is already starting to paw at their clothes. They are entirely too dressed for what’s about to happen.

His husband is quick on the uptake and snaps his fingers and they’re naked. The slick on his thighs is chilled by the sudden rush of cool air, but if anything the temperature change just adds another layer of arousal. If Alec wasn’t already gushing slick like he was in heat he definitely would be now.

“By the angel, Magnus,” Alec groans, “have I mentioned how thankful I am for your magic lately?”

Magnus hums, nipping at his shoulder. “It’s always nice to hear, Alexander,” he says with a grin.

Their cocks slide together as they rut against each other and it’s so perfect Alec doesn’t dare hold back the whimpering praises and moans of Magnus’ name. Alec’s nipple is taken between those perfect lips and if this keeps going the way it is Alec won’t last long enough.

“Magnus, please.”

The warlock pulls away from his chest with a final peck and looks into his eyes. “What is it, angel?”

“ _Magnus_.”

Looking to proud of himself, Magnus moves over to his other nipple. “I figured I could help your body get used to nursing, stimulate the gland, y’know?”

Alec rolls his eyes and lets out a breathless laugh. “Shouldn’t you be focusing on actually getting me pregnant first?”

Magnus makes a noncommittal noise. “It’s never too early to start the groundwork, darling.”

Alec shakes his head and wraps his legs around Magnus’ hips, pressing his heels into the meat of his husband’s ass. “Want you now, want you filling me up.”

“Want me to knot that greedy hole of yours? Want me breeding you already?”

He groans and throws his head back. “Magnus don’t tease me with dirty talk,” he whines.

“Hmm, but you get so sweet when I tease you.”

Alec frowns up at him. “Think how sweet I’ll be when your come takes, when you can start smelling the shift in my scent from a successful breeding.”

It’s a bit of a cheap shot because Magnus loves his scent, but he’ll play dirty if it means Magnus will breed him already.

The warlock’s gaze looks almost predatory and then there are two fingers at his hole. He sighs happily, arching his back to try and get the fingers to finally breech his entrance. The slight burn from the stretch feels amazing and he clenches around the appendages to hear Magnus practically purr at the action.

“Oh _Alexander_ ,” Magnus murmurs, “You’re so impatient to be filled, aren’t you.” He scissors his fingers expertly to loosen him. “Wet and ready to take me.”

The flush of his skin definitely probably pinks down to his chest but Magnus isn’t wrong. He wants Magnus’s cock deep inside him, gliding against his prostate with each thrust of his hips. He wants the knot that will lock them together and the hot splash of come painting his insides.

He wants to be bred.

Now.

He must have made some sort of desperate noise because Magnus is hushing him with gentle kisses to his heated skin. “Patience, angel.” Magnus wiggles another finger into him and Alec gasps. “Just want to make sure you’re plenty ready to take my cock.”

Frantic nodding is all Alec can manage to express, already caught up in the blissful haze as his instincts come closer to the forefront. He feels his hole relax around Magnus’ fingers and lavishes in the growl of approval from his husband.

“Will you come for me before I fuck you?” Magnus asks, abusing Alec’s prostate like it’s the replay button on his favorite song. “Can you do that for me, angel?”

“I’m s-so close, Magnus,” Alec says breathlessly.

Magnus presses against Alec’s prostate and moves his free hand down to his belly. “You’re going to look so beautiful with my child in you.” He cups the hard muscles on Alec’s stomach. “I’m going to love watching your belly grow heavier and heavier with each passing week.” He leans up so he can whisper in Alec’s ear. “And everyone is going to know exactly how well I’ve bred you, my pretty omega.”

White takes over his vision as Alec comes with a shout, his orgasm encouraged out of him with Magnus’s words. He doesn’t feel himself paint his torso with his come, but he opens his mouth when two wet fingers are brought to his lips.

His come is salty with a hint of sweetness on his tongue and he manages to open his eyes and gives Magnus a dopey grin. His husband looks at him captivated and voracious in equal parts and Alec wraps his arms around his neck.

They bask in the small stall in their lovemaking, content to just stare back at each other. Alec tilts his head to brush a kiss against Magnus’s lips and it’s like they’ve come full circle back to trading lazy kisses. Magnus is still hard against his thigh but his husband doesn’t seem in a rush to keep going just yet.

“You okay?” Alec asks because Magnus usually has something witty to say.

Magnus nods, pressing their foreheads together. “I just want you to know that us getting pregnant isn’t necessarily going to be easy as fucking once,” Magnus replies as if they haven’t had this conversation when Alec had first brought up starting a family. ”Warlocks are notorious-“

“For having low fertility,” Alec fills in. “I know it won’t be smooth sailing, but we can try as often as you’re willing.”

“Trust me, it has nothing to be with not being willing,” Magnus illustrates this with a roll of his hips. “I just don’t want to get your hopes up if this doesn’t take.”

Alec gives him what he hopes looks like a reassuring smile. “Magnus, I promise that whether I get pregnant or not this time, it’s fine. If it doesn’t happen, well- then I guess we’ll just keep trying.”

“I’m all for effort.”

“Ah yes, the truest hardship, having to have sex with my husband over and over.”

Magnus snorts at Alec’s comment and that mischievous sparkle appears in his eyes. “Maybe we’ll even try a round or two at your office. Imagine, the Inquisitor splayed out on his desk with his alpha warlock husband pounding into him as the precious Inquisitor lets out a sweet arrangement of noises.”

He gives Magnus an incredulous look. “We are not fucking in my office, I have to do work in there,” Alec says. “If we have breeding sex in my office all I’m going to think about is you breeding me and then I’ll never get any work done.”

The warlock sighed and rolled his eyes. “It would give me a reason to redecorate your office, and I’m always up for some redecorating.” He pinches Alec’s side with a grin. “I’m just saying, having sex in your office would be exciting.”

Alec shook his head fondly at his husband. “Maybe too exciting for now.”

“Hm… Pandemonium would be fun.”

The Shadowhunter gave Magnus an incredulous look. “Pandemonium? That’s way less private than my office.”

“That wasn’t a ‘no’ and does this suggestion change your mind about office sex?”

Shrugging his shoulders, Alec nudged Magnus ass with his foot. “Maybe,” he rolled his eyes as Magnus spelled a bit of confetti to float around them. “Okay, okay, enough talking.”

“You ready to continue?” Magnus asks, his fingers carding through the short hairs that tickle Alec’s neck.

“Are you kidding? I thought we were waiting on you,” Alec teases.

The faux indignation that colors Magnus’ face is enough to send Alec into a fit of laughter. “Oh, Alexander you’re going to get it.”

He grins and spreads his legs a bit wider. “I’m ready.”

Shifting his knees, Magnus grabs his dick and guides the head to Alec’s hole and pushes in. The combination of Magnus’ stretching and Alec’s own slick makes it easy for Magnus to slide right to the hilt. Alec lets out a blissful sigh and clenches around Magnus’ dick.

“You feel incredible,” Alec slurs, already rolling his hips to try and get the warlock’s cock to rub against his prostate. “Always feel so good.”

A hum of approval sounds from the man above him. “Oh darling, you have no idea how beautiful you look when you’re hungry for my cock, greedy for pleasure,” Magnus praises. His husband draws out of him and Alec whimpers at the emptiness before Magnus is thrusting back in. The head of Magnus’ cock kisses his prostate and not for the first time Alec wonders if they were made for each other.

With Alec’s gratifying moans of encouragement, Magnus pistons his dick in and out of Alec. The sounds of Magnus slamming into Alec echoed obscenely throughout their loft, loud and wet. Alec pushes back onto Magnus’ thrusts as best he can from where Magnus has him pinned to the sheets. His dick leaks against his belly, tears leaking from his eyes.

He feels so wonderfully full and he can’t get enough.

Alec tries to babble out praises, but struggles to get out more than a litany of Magnus’ name amidst the moans and keening that leaves his mouth. “Magnus,” he breathes out, wrapping his legs tighter around Magnus’ hips so that his husband has to slow his thrusting down to a grueling grind. “W-want your knot, p-please.”

Magnus lets out a mixture of a groan and a purr of delight. “Shh, my beautiful Alexander,” he coos, “you ready for me to officially breed you?”

Alec nods and uses his core muscles to tilt his hips up farther. “Please, Mags.”

Magnus moans Alec’s name, his lips attacking Alec’s own as he shivers through his orgasm, knot filling and fastening them together. Alec arches into Magnus and moans, cock twitching as he cums between them.

They’re both panting, hearts hammering in their chest and Alec feels complete. Magnus’ seed fills up every crevice inside him and he floats amidst the post-orgasmic haze. He almost doesn’t notice Magnus’ fingers loosen their grip they had on the meat of his thighs.

Magnus gently shifts them so they’re lying on their sides, making sure that they don’t part enough to tug at his knot fit snugly in his husband. Alec feels a pleasant vibrating coming from Magnus as he realizes his alpha is purring. His husband’s nose is tucked into Alec’s hair and his hands are gently stroking the expanse of his back with his nails. Alec smiles and answers with a purr of his own.

“My beautiful angel,” Magnus murmurs, moving his head down to swipe his tongue across Alec’s scent gland. “What did I ever do to deserve you, Alexander?”

Alec chuckles, still feeling drunk from his orgasm. “That’s my line, Magnus,” he slurs, idly carding his fingers through Magnus’ hair. “You’re perfect.”

They bask in their haze as they wait for Magnus’ knot to go down, and Alec moans when he feels Magnus roll his hips lazily into him. He clenches down on his knot, trying to keep everything inside but he knows when Magnus’ knot goes down his husband’s cum will start leaking out.

“Do you think it took?” Magnus asks, moving one of his hands down to caress the plains of Alec’s taught stomach.

Alec hums thoughtfully and shrugs. “I doubt we’d know already,” he pulls his head back so he can look Magnus in the eye, “But there’s no harm in going a second round.”

Magnus’ grin is positively devilish. “Oh, Alexander, I plan to breed you until I can feel a babe growing in your womb,” he presses his lips against Alec’s chastely, “and then I plan on worshipping you like you deserve.”

“I can’t wait.”

**Author's Note:**

> Thank you so much for reading! If you have time, I'd love to hear what you thought of this fic. 
> 
> If you have a prompt you'd like me to write, just either request it in the comments or send me an ask on my tumblr, [cakelanguage](https://cakelanguage.tumblr.com/).


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